The von Economo neurons in frontoinsular and anterior cingulate cortex in great apes and humans

Moral judgment in patients with behavioral variant of frontotemporal dementia and amyotrophic lateral sclerosis: no impairment of the moral position, but rather its execution

OBJECTIVE

To investigate moral judgment competence in patients with the behavioral variant frontotemporal dementia (bvFTD) compared to amyotrophic lateral sclerosis (ALS) and controls.

METHODS

N = 12 bvFTD, N = 22 ALS patients and N = 19 neurological unimpaired controls were examined. In the 'Moral Competence Test' (MCT), participants had to evaluate two moral dilemmas by predefined arguments to measure the consistency of their moral judgments. The 'Ethics Position Questionnaire' (EPQ) addresses whether individuals prefer binding ethical standards, the Idler Index of Religiosity (IIR) measures the level of religiosity. Cognition was assessed with the CERAD-plus.

RESULTS

BvFTD and ALS patients exhibited a similar moral position as healthy controls but a significantly lower judgment consistency in the MCT. MCT performance was independent from general cognitive functioning and not associated with moral orientation and religiosity.

CONCLUSIONS

Our findings indicate that not the moral position itself seems to be impaired in patients with bvFTD, but rather their competence to transfer it into situational decisions. The fact that ALS patients have similar problems in applying moral principles in a consistent manner might indicate a deficit in execution of moral judgment, and this is in line with studies suggesting a damage of specific cerebral structures.

Structural Connectivity of the Anterior Cingulate Cortex, Claustrum, and the Anterior Insula of the Mouse

The claustrum is a narrow subcortical brain structure that resides between the striatum and insular cortex. The function of the claustrum is not fully described, and while our previous work supports a role for the claustrum in top-down cognitive control of action, other evidence suggests the claustrum may be involved in detecting salient changes in the external environment. The anterior cingulate cortex (ACC) and the anterior insular (aINS) are the two major participants in the salience network of human brain regions that activate in response to salient stimuli. While bidirectional connections between the ACC and the claustrum exist from mouse to non-human primate, the aINS connectivity with claustrum remains unclear, particularly in mouse. Here, we explored structural connections of the aINS with the claustrum and ACC through adeno-associated virus neuronal tract tracer injections into the ACC and aINS of the mouse. We detected sparse projections from the claustrum to the aINS and diffuse projections from the aINS to the borders of the claustrum were observed in some cases. In contrast, the insular cortex and endopiriform nucleus surrounding the claustrum had rich interconnectivity with aINS. Additionally, we observed a modest interconnectivity between ACC and the aINS. These data support the idea that claustrum neuron responses to salient stimuli may be driven by the ACC rather than the aINS.

Appetite, Metabolism and Hormonal Regulation in Normal Ageing and Dementia

Feeding and nutrition follow the growth trajectory of the course of life. The profound physiological changes that human body experiences during ageing affect separate aspects of food intake, from tastant perception to satiety. Concurrent morbidities, such as neurodegeneration, as seen in dementia, and metabolic syndrome, may further shape nutritional behaviours, status and adequacy. In an effort to fill the gap between the exhausting basic research and the actual needs of professionals caring for the exponentially expanding ageing population, the current review addresses major factors relevant to appetite and eating disturbances. Does age alter the perception of food modalities? Is food generally still perceived as alluring and delicious with age? Is there an interplay between ageing, cognitive decline, and malnutrition? What tools can we adopt for proper and timely monitoring? Finally, what anatomical and pathophysiological evidence exists to support a hypothesis of central regulation of metabolic perturbations in normal and accelerated cognitive impairment, and how can we benefit from it in health practice?

Emotions and the Right Hemisphere: Can New Data Clarify Old Models?

Models advanced to explain hemispheric asymmetries in representation of emotions will be discussed following their historical progression. First, the clinical observations that have suggested a general dominance of the right hemisphere for all kinds of emotions will be reviewed. Then the experimental investigations that have led to proposal of a different hemispheric specialization for positive versus negative emotions (valence hypothesis) or, alternatively, for approach versus avoidance tendencies (motivational hypothesis) will be surveyed. The discussion of these general models will be followed by a review of recent studies which have documented laterality effects within specific brain structures, known to play a critical role in different components of emotions, namely the amygdata in the computation of emotionally laden stimuli, the ventromedial prefrontal cortex in the integration between cognition and emotion and in the control of impulsive reactions and the anterior insula in the conscious experience of emotion. Results of these recent investigations support and provide an updated integrated version of early models assuming a general right hemisphere dominance for all kinds of emotions.

Differential insular cortex subregional vulnerability to α-synuclein pathology in Parkinson's disease and dementia with Lewy bodies

Aim

The insular cortex consists of a heterogenous cytoarchitecture and diverse connections and is thought to integrate autonomic, cognitive, emotional and interoceptive functions to guide behaviour. In Parkinson's disease (PD) and dementia with Lewy bodies (DLB), it reveals α‐synuclein pathology in advanced stages. The aim of this study is to assess the insular cortex cellular and subregional vulnerability to α‐synuclein pathology in well‐characterized PD and DLB subjects.

Methods

We analysed postmortem insular tissue from 24 donors with incidental Lewy body disease, PD, PD with dementia (PDD), DLB and age‐matched controls. The load and distribution of α‐synuclein pathology and tyrosine hydroxylase (TH) cells were studied throughout the insular subregions. The selective involvement of von Economo neurons (VENs) in the anterior insula and astroglia was assessed in all groups.

Results

A decreasing gradient of α‐synuclein pathology load from the anterior periallocortical agranular towards the intermediate dysgranular and posterior isocortical granular insular subregions was found. Few VENs revealed α‐synuclein inclusions while astroglial synucleinopathy was a predominant feature in PDD and DLB. TH neurons were predominant in the agranular and dysgranular subregions but did not reveal α‐synuclein inclusions or significant reduction in density in patient groups.

Conclusions

Our study highlights the vulnerability of the anterior agranular insula to α‐synuclein pathology in PD, PDD and DLB. Whereas VENs and astrocytes were affected in advanced disease stages, insular TH neurons were spared. Owing to the anterior insula's affective, cognitive and autonomic functions, its greater vulnerability to pathology indicates a potential contribution to nonmotor deficits in PD and DLB.

A neuroscientific perspective on basic psychological needs

OBJECTIVE

Self-determination theory's (SDT) most basic propositions are, first, that all people possess an inherent set of psychological needs and, second, that autonomy, competence, and relatedness are the three critical psychological satisfactions needed to maintain and promote personal growth and well-being. In this article, we identify the neural basis of the psychological needs and, in doing so, seek to advance the integration of SDT and neuroscience.

METHOD

We examine the neural underpinnings of SDT-based motivational states and traits for autonomy, competence, and relatedness. To study motivational states, participants are exposed to situational conditions known to affect their psychological needs, and neuroscience methods (e.g., fMRI) are used to examine changes in their brain activity. To study motivational traits, participants complete self-report trait measures that are then correlated with their brain activity observed during need-satisfying activities.

RESULTS

For both motivational states and traits and across all three needs, intrinsic satisfaction is associated with striatum-based reward processing, anterior insula-based subjective feelings, and the integration of these subjective feelings with reward-based processing.

CONCLUSIONS

Psychological need satisfaction is associated with striatum activity, anterior insula activity, and the functional coactivation between these two brain areas. Given these findings, it is now clear that several opportunities exist to integrate SDT motivational constructs with neuroscientific study, so we suggest eight new questions for future research.

The regional homogeneity of cingulate-precuneus regions: The putative biomarker for depression and anxiety

OBJECTIVES

In addition to clinical interview, the modern putative biomarker to differentiate depression and anxiety would be warranted. The translational medicine characteristics of neuroimaging, such as the regional homogeneity (ReHo), is an option for depression and anxiety. Therefore we designed this study trying to identify the biomarker pattern for depression and anxiety.

METHODS

Resting-state functional magnetic resonance imaging was acquired for 53 patients with first-episode medicine-naïve major depressive disorder (MDD), 53 first-episode medicine-naïve patients with panic disorder (PD) and 54 controls. The calculation of ReHo was performed. The ANOVA repeated measures were applied for the 3 groups to investigate the putative differences between MDD and PD (FDR corrected p < 0.05).

RESULTS

After multiple comparisons, the major findings of ReHo were found in the bilateral anterior cingulate cortex and bilateral precuneus. MDD group had lower ReHo values than PD group in the left anterior cingulate cortex. MDD group had significant alterations of ReHo in the left anterior cingulate cortex and bilateral precuneus when compared to controls. PD group had alterations in the bilateral precuneus when compared to controls.

CONCLUSION

The specific cingulate alterations might be a putative ReHo biomarker to differentiate MDD from PD in cingulate-precuneus background for ReHo alterations.

Gray matter volume of the anterior insular cortex and social networking

In human life, social context requires the engagement in complex interactions among individuals as the dynamics of social networks. The evolution of the brain as the neurological basis of the mind must be crucial in supporting social networking. Although the relationship between social networking and the amygdala, a small but core region for emotion processing, has been reported, other structures supporting sophisticated social interactions must be involved and need to be identified. In this study, we examined the relationship between morphology of the anterior insular cortex (AIC), a structure involved in basic and high-level cognition, and social networking. Two independent cohorts of individuals (New York group n = 50, Beijing group n = 100) were recruited. Structural magnetic resonance images were acquired and the social network index (SNI), a composite measure summarizing an individual's network diversity, size, and complexity, was measured. The association between morphological features of the AIC, in addition to amygdala, and the SNI was examined. Positive correlations between the measures of the volume as well as sulcal depth of the AIC and the SNI were found in both groups, while a significant positive correlation between the volume of the amygdala and the SNI was only found in the New York group. The converging results from the two groups suggest that the AIC supports network-level social interactions.

Von Economo neurons of the anterior cingulate across the lifespan and in Alzheimer's disease

BACKGROUND

Throughout the human aging lifespan, neurons acquire an unusually high burden of wear and tear; this is likely why age is considered the strongest risk factor for the development of Alzheimer's Disease (AD). Von Economo neurons (VENs) are rare, spindle-shaped cells mostly populated in anterior cingulate cortex. In a prior study, "SuperAgers" (individuals older than 80 years of age with outstanding memory ability) showed higher VEN densities compared to elderly controls with average memory, and those with amnestic Mild Cognitive Impairment (aMCI). The intrinsic vulnerabilities of these neurons are unclear, and their contribution to neurodegeneration is unknown. The current study investigated the influence of age and the severity of Alzheimer's disease (AD) on VEN density.

METHODS

VEN and total neuronal densities were quantitated using unbiased stereological methods in the anterior cingulate cortex of postmortem samples from the following subject groups: younger controls (age 20-60), SuperAgers, cognitively average elderly controls (age 65+), individuals diagnosed antemortem with aMCI, and individuals diagnosed antemortem with dementia of AD (N = 5, per group).

RESULTS

The AD group showed significantly lower VEN density compared to younger and older controls (p < .05), but not compared to the aMCI group, and VENs bearing neurofibrillary tangles were discovered in AD cases. The aMCI group showed lower VEN density than elderly controls, but this was not significant. There was a significant negative correlation between VEN density and Braak stages of AD (p < .001). Consistent with prior findings, SuperAgers showed highest mean VEN density, even when compared to younger cases.

CONCLUSIONS

VENs in human anterior cingulate cortex are vulnerable to AD pathology, particularly in later stages of pathogenesis. Their densities do not change throughout aging in individuals with average cognition, and they are more numerous in SuperAgers.

Von Economo Neurons and Fork Cells: A Neurochemical Signature Linked to Monoaminergic Function

The human anterior cingulate and frontoinsular cortices are distinguished by 2 unique Layer 5 neuronal morphotypes, the von Economo neurons (VENs) and fork cells, whose biological identity remains mysterious. Insights could impact research on diverse neuropsychiatric diseases to which these cells have been linked. Here, we leveraged the Allen Brain Atlas to evaluate mRNA expression of 176 neurotransmitter-related genes and identified vesicular monoamine transporter 2 (VMAT2), gamma-aminobutyric acid (GABA) receptor subunit θ (GABRQ), and adrenoreceptor α-1A (ADRA1A) expression in human VENs, fork cells, and a minority of neighboring Layer 5 neurons. We confirmed these results using immunohistochemistry or in situ hybridization. VMAT2 and GABRQ expression was absent in mouse cerebral cortex. Although VMAT2 is known to package monoamines into synaptic vesicles, in VENs and fork cells its expression occurs in the absence of monoamine-synthesizing enzymes or reuptake transporters. Thus, VENs and fork cells may possess a novel, uncharacterized mode of cortical monoaminergic function that distinguishes them from most other mammalian Layer 5 neurons.

Interactions of Insula Subdivisions-Based Networks with Default-Mode and Central-Executive Networks in Mild Cognitive Impairment

Interactions between the brain networks and subnetworks are crucial for active and resting cognitive states. Whether a subnetwork can restore the adequate function of the parent network whenever a disease state affects the parent network is unclear. Investigations suggest that the control of the anterior insula-based network (AIN) over the default-mode network (DMN) and central-executive network (CEN) is decreased in individuals with mild cognitive impairment (MCI). Here, we hypothesized that the posterior insula-based network (PIN) attempts to compensate for this decrease. To test this, we compared a group of MCI and normal cognitive individuals. A dynamical causal modeling method has been employed to investigate the dynamic network controls/modulations. We used the resting state functional MRI data, and assessed the interactions of the AIN and of the PIN, respectively, over the DMN and CEN. We found that the greater control of AIN than that of DMN (Wilcoxon rank sum: Z = 1.987; p = 0.047) and CEN (Z = 3.076; p = 0.002) in normal group and the lower (impaired) control of AIN than that of CEN (Z = 8.602; p = 7.816 × 10^-18). We further revealed that the PIN control was significantly higher than that of DMN (Z = 6.608; p = 3.888 × 10^-11) and CEN (Z = 6.429; p = 1.278 × 10^-10) in MCI group where the AIN was impaired, but that control was significantly lower than of DMN (Z = 5.285; p = 1.254 × 10^-7) and CEN (Z = 5.404; p = 6.513 × 10^-8) in normal group. Finally, the global cognitive test score assessed using Montreal cognitive assessment and the network modulations were correlated (Spearman's correlation: r = 0.47; p = 3.76 × 10^-5 and r = -0.43; p = 1.97 × 10^-4). These findings might suggest the flexible functional profiles of AIN and PIN in normal aging and MCI.

Autism spectrum disorder: neuropathology and animal models

Autism spectrum disorder (ASD) has a major impact on the development and social integration of affected individuals and is the most heritable of psychiatric disorders. An increase in the incidence of ASD cases has prompted a surge in research efforts on the underlying neuropathologic processes. We present an overview of current findings in neuropathology studies of ASD using two investigational approaches, postmortem human brains and ASD animal models, and discuss the overlap, limitations, and significance of each. Postmortem examination of ASD brains has revealed global changes including disorganized gray and white matter, increased number of neurons, decreased volume of neuronal soma, and increased neuropil, the last reflecting changes in densities of dendritic spines, cerebral vasculature and glia. Both cortical and non-cortical areas show region-specific abnormalities in neuronal morphology and cytoarchitectural organization, with consistent findings reported from the prefrontal cortex, fusiform gyrus, frontoinsular cortex, cingulate cortex, hippocampus, amygdala, cerebellum and brainstem. The paucity of postmortem human studies linking neuropathology to the underlying etiology has been partly addressed using animal models to explore the impact of genetic and non-genetic factors clinically relevant for the ASD phenotype. Genetically modified models include those based on well-studied monogenic ASD genes (NLGN3, NLGN4, NRXN1, CNTNAP2, SHANK3, MECP2, FMR1, TSC1/2), emerging risk genes (CHD8, SCN2A, SYNGAP1, ARID1B, GRIN2B, DSCAM, TBR1), and copy number variants (15q11-q13 deletion, 15q13.3 microdeletion, 15q11-13 duplication, 16p11.2 deletion and duplication, 22q11.2 deletion). Models of idiopathic ASD include inbred rodent strains that mimic ASD behaviors as well as models developed by environmental interventions such as prenatal exposure to sodium valproate, maternal autoantibodies, and maternal immune activation. In addition to replicating some of the neuropathologic features seen in postmortem studies, a common finding in several animal models of ASD is altered density of dendritic spines, with the direction of the change depending on the specific genetic modification, age and brain region. Overall, postmortem neuropathologic studies with larger sample sizes representative of the various ASD risk genes and diverse clinical phenotypes are warranted to clarify putative etiopathogenic pathways further and to promote the emergence of clinically relevant diagnostic and therapeutic tools. In addition, as genetic alterations may render certain individuals more vulnerable to developing the pathological changes at the synapse underlying the behavioral manifestations of ASD, neuropathologic investigation using genetically modified animal models will help to improve our understanding of the disease mechanisms and enhance the development of targeted treatments.

Structural deficits in salience network regions are associated with increased impulsivity and compulsivity in alcohol dependence

BACKGROUND

Convergent preclinical and clinical evidence has linked the anterior insula to impulsivity and alcohol-associated compulsivity. The anterior insula is functionally connected to the anterior cingulate cortex, together comprising the major nodes of the salience network, which serves to signal salient events, including negative consequences. Clinical studies have found structural and functional alterations in the anterior insula and anterior cingulate cortices of alcohol dependent individuals. No studies have yet investigated the association between morphometric abnormalities in salience network regions and the phenotype of high levels of impulsivity and compulsivity seen in alcohol dependent individuals.

METHODS

In the current study, we compared self-report impulsivity, decisional impulsivity, self-report compulsivity, and structural neuroimaging measures in a sample of alcohol dependent individuals (n=60) and a comparison group of healthy controls (n=49). From the structural magnetic resonance images, we calculated volume and cortical thickness for 6 regions of interest: left and right anterior insula, posterior insula, and anterior cingulate.

RESULTS

We found that alcohol dependent individuals had smaller anterior insula and anterior cingulate volumes, as well as thinner anterior insula cortices. There were no group differences in posterior insula morphometry. Anterior insula and anterior cingulate structural measures were negatively associated with self-report impulsivity, decisional impulsivity, and compulsivity measures.

CONCLUSIONS

Our results suggest that addiction endophenotypes are associated with salience network morphometry in alcohol addiction. These relationships indicate that salience network hubs represent potential treatment targets for impulse control disorders, including alcohol addiction.

Interactions of the Salience Network and Its Subsystems with the Default-Mode and the Central-Executive Networks in Normal Aging and Mild Cognitive Impairment

Previous functional magnetic resonance imaging (fMRI) investigations suggest that the intrinsically organized large-scale networks and the interaction between them might be crucial for cognitive activities. A triple network model, which consists of the default-mode network, salience network, and central-executive network, has been recently used to understand the connectivity patterns of the cognitively normal brains versus the brains with disorders. This model suggests that the salience network dynamically controls the default-mode and central-executive networks in healthy young individuals. However, the patterns of interactions have remained largely unknown in healthy aging or those with cognitive decline. In this study, we assess the patterns of interactions between the three networks using dynamical causal modeling in resting state fMRI data and compare them between subjects with normal cognition and mild cognitive impairment (MCI). In healthy elderly subjects, our analysis showed that the salience network, especially its dorsal subnetwork, modulates the interaction between the default-mode network and the central-executive network (Mann-Whitney U test; p < 0.05), which was consistent with the pattern of interaction reported in young adults. In contrast, this pattern of modulation by salience network was disrupted in MCI (p < 0.05). Furthermore, the degree of disruption in salience network control correlated significantly with lower overall cognitive performance measured by Montreal Cognitive Assessment (r = 0.295; p < 0.05). This study suggests that a disruption of the salience network control, especially the dorsal salience network, over other networks provides a neuronal basis for cognitive decline and may be a candidate neuroimaging biomarker of cognitive impairment.

Enhancing our brains: Genomic mechanisms underlying cortical evolution

Our most distinguishing higher cognitive functions are controlled by the cerebral cortex. Comparative studies detail abundant anatomical and cellular features unique to the human developing and adult neocortex. Emerging genomic studies have further defined vast differences distinguishing developing human neocortices from related primates. These human-specific changes can affect gene function and/or expression, and result from structural variations such as chromosomal deletions and duplications, or from point mutations in coding and noncoding regulatory regions. Here, we review this rapidly growing field which aims to identify and characterize genetic loci unique to the human cerebral cortex. We catalog known human-specific genomic changes distinct from other primates, including those whose function has been interrogated in animal models. We also discuss how new model systems and technologies such as single cell RNA sequencing, primate iPSCs, and gene editing, are enabling the field to gain unprecedented resolution into function of these human-specific changes. Some neurological disorders are thought to uniquely present in humans, thus reinforcing the need to comprehensively understand human-specific gene expression in the developing brain.

Evolution of the Human Nervous System Function, Structure, and Development

The nervous system-in particular, the brain and its cognitive abilities-is among humans' most distinctive and impressive attributes. How the nervous system has changed in the human lineage and how it differs from that of closely related primates is not well understood. Here, we consider recent comparative analyses of extant species that are uncovering new evidence for evolutionary changes in the size and the number of neurons in the human nervous system, as well as the cellular and molecular reorganization of its neural circuits. We also discuss the developmental mechanisms and underlying genetic and molecular changes that generate these structural and functional differences. As relevant new information and tools materialize at an unprecedented pace, the field is now ripe for systematic and functionally relevant studies of the development and evolution of human nervous system specializations.

Insula-based networks in professional musicians: Evidence for increased functional connectivity during resting state fMRI

Despite considerable research on experience-dependent neuroplasticity in professional musicians, detailed understanding of an involvement of the insula is only now beginning to emerge. We investigated the effects of musical training on intrinsic insula-based connectivity in professional classical musicians relative to nonmusicians using resting-state functional MRI. Following a tripartite scheme of insula subdivisions, coactivation profiles were analyzed for the posterior, ventral anterior, and dorsal anterior insula in both hemispheres. While whole-brain connectivity across all participants confirmed previously reported patterns, between-group comparisons revealed increased insular connectivity in musicians relative to nonmusicians. Coactivated regions encompassed constituents of large-scale networks involved in salience detection (e.g., anterior and middle cingulate cortex), affective processing (e.g., orbitofrontal cortex and temporal pole), and higher order cognition (e.g., dorsolateral prefrontal cortex and the temporoparietal junction), whereas no differences were found for the reversed group contrast. Importantly, these connectivity patterns were stronger in musicians who experienced more years of musical practice, including also sensorimotor regions involved in music performance (M1 hand area, S1, A1, and SMA). We conclude that musical training triggers significant reorganization in insula-based networks, potentially facilitating high-level cognitive and affective functions associated with the fast integration of multisensory information in the context of music performance. Hum Brain Mapp 38:4834-4849, 2017. © 2017 Wiley Periodicals, Inc.

Functional Connectivity Differences in the Insular Sub-regions in Migraine without Aura: A Resting-State Functional Magnetic Resonance Imaging Study

Objective: The objective of this study was to investigate resting-state functional connectivity (FC) differences in insular sub-regions during the interictal phase in patients with migraine without aura (MWoA). Methods: Forty-nine MWoA patients (MWoA group) and 48 healthy individuals (healthy control group) were recruited for this study. All of the subjects underwent neurological examination and magnetic resonance imaging (MRI). The MRI data were processed using Brat 1.0 software to obtain a whole-brain FC diagram and using Rest 1.8 software to obtain the FC z-score of the sub-regions of both insulas (six sub-regions on each side). Therefore, there were a total of 12 regions of interest (ROIs) that were used as seed points for the statistical analysis. Results: There was abnormal FC between the insular sub-regions and multiple brain regions in the MWoA patients compared with the healthy control group, and a clear laterality was also observed. In addition, the FC z-score of certain sub-regions was negatively correlated with the disease duration. Conclusion: Different insular sub-regions are functionally associated with different regions of the brain and therefore have different functions. In MWoA, the FC between the insular sub-regions and other brain regions was mostly reduced, while a small amount was increased; additionally, the FC may be ipsilateral with a right-side advantage. Variations in the FC of insular sub-regions can be observed as an important indicator of MWoA.

Neural Mechanisms of Updating under Reducible and Irreducible Uncertainty

Adaptive decision making depends on an agent's ability to use environmental signals to reduce uncertainty. However, because of multiple types of uncertainty, agents must take into account not only the extent to which signals violate prior expectations but also whether uncertainty can be reduced in the first place. Here we studied how human brains of both sexes respond to signals under conditions of reducible and irreducible uncertainty. We show behaviorally that subjects' value updating was sensitive to the reducibility of uncertainty, and could be quantitatively characterized by a Bayesian model where agents ignore expectancy violations that do not update beliefs or values. Using fMRI, we found that neural processes underlying belief and value updating were separable from responses to expectancy violation, and that reducibility of uncertainty in value modulated connections from belief-updating regions to value-updating regions. Together, these results provide insights into how agents use knowledge about uncertainty to make better decisions while ignoring mere expectancy violation.SIGNIFICANCE STATEMENT To make good decisions, a person must observe the environment carefully, and use these observations to reduce uncertainty about consequences of actions. Importantly, uncertainty should not be reduced purely based on how surprising the observations are, particularly because in some cases uncertainty is not reducible. Here we show that the human brain indeed reduces uncertainty adaptively by taking into account the nature of uncertainty and ignoring mere surprise. Behaviorally, we show that human subjects reduce uncertainty in a quasioptimal Bayesian manner. Using fMRI, we characterize brain regions that may be involved in uncertainty reduction, as well as the network they constitute, and dissociate them from brain regions that respond to mere surprise.

Racial Differences in Insular Connectivity and Thickness and Related Cognitive Impairment in Hypertension

Hypertensive African–Americans have a greater risk of cognitive impairment than hypertensive Caucasian–Americans. The neural basis of this increased risk is yet unknown. Neuroimaging investigations suggest that the normal neural activity comprises complex interactions between brain networks. Recent studies consistently demonstrate that the insula, part of the salience network, provides modulation effects (information flow) over the default-mode and central-executive networks in cognitively normal subjects, and argue that the modulation effect is declined in cognitive impairment. The purpose of this study is to examine the information flow at the nodes of three networks using resting state functional magnetic resonance imaging (MRI) data in cognitively impaired hypertensive individuals with the African–Americans and the Caucasian–Americans races, and to compare the thickness of impaired node between two racial groups. Granger causality methodology was used to calculate information flow between networks using resting state functional MRI data, and FreeSurfer was used to measure cortical thickness from T1-weighted structural images. We found that negative information flow of the insula in both African–Americans and Caucasian–Americans, which was in contrast with previously reported positive information flow in this region of normal individuals. Also, significantly greater negative information flow in insula was found in African–Americans than Caucasian–Americans (Wilcoxon rank sum; Z = 2.06; p < 0.05). Significantly, lower insula thickness was found in African–Americans compared with Caucasian–Americans (median = 2.797 mm vs. 2.897 mm) (Wilcoxon rank sum; Z = 2.09; p < 0.05). Finally, the insula thickness correlated with the global cognitive testing measured by Montreal cognitive assessment (Spearman’s correlation; r = 0.30; p < 0.05). These findings suggest that the insula is a potential biomarker for the racial disparity in cognitive impairment of hypertensive individuals.

Resting-state functional connectivity between right anterior insula and right orbital frontal cortex correlate with insight level in obsessive-compulsive disorder

Few studies have explored the neurobiological basis of insight level in obsessive-compulsive disorder (OCD), though the salience network (SN) has been implicated in insight deficits in schizophrenia. This study was then designed to investigate whether resting-state (rs) functional connectivity (FC) of SN was associated with insight level in OCD patients. We analyzed rs-functional magnetic resonance imaging (fMRI) data from 21 OCD patients with good insight (OCD-GI), 19 OCD patients with poor insight (OCD-PI), and 24 healthy controls (HCs). Seed-based whole-brain FC and ROI (region of interest)-wise connectivity analyses were performed with seeds/ROIs in the bilateral anterior insula (AI) and dorsal anterior cingulate cortex (dACC). The right AI-right medial orbital frontal cortex (mOFC) connectivity was found to be uniquely decreased in the OCD-PI group, and the value of this aberrant connectivity correlated with insight level in OCD patients. In addition, we found that the OCD-GI group had significantly increased right AI-left dACC connectivity within the SN, relative to HCs (overall trend for groups: OCD-GI > OCD-PI > HC). Our findings suggest that abnormal right AI-right mOFC FC may mediate insight deficits in OCD, perhaps due to impaired encoding and integration of self-evaluative information about OCD-related beliefs and behaviors. Our findings indicate a SN connectivity dissociation between OCD-GI and OCD-PI patients and support the notion of considering OCD-GI and OCD-PI as two distinct disorder subtypes.

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We examined the functional connectivity of SN in OCD-GI and OCD-PI.

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OCD-PI patients had decreased right AI-right mOFC connectivity.

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Right AI- right mOFC connectivity correlated with insight level in OCD.

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OCD-GI patients had elevated right AI-left dACC connectivity within SN.

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These results are helpful toward elucidating insight presentation in OCD.

The Insula: An Underestimated Brain Area in Clinical Neuroscience, Psychiatry, and Neurology

Supported by recent human neuroimaging studies, the insula is re-emerging as an important brain area not only in the physiological understanding of the brain, but also in pathological contexts in clinical research. In this opinion article, we briefly introduce the anatomical and histological features of the human insula. We then summarize the physiological functions of the insula and underscore its pathological roles in psychiatric and neurological disorders that have long been underestimated. We finally propose possible strategies through which the role of the insula may be further understood for both basic and clinical neuroscience.

The Insula: A "Hub of Activity" in Migraine

The insula, a "cortical hub" buried within the lateral sulcus, is involved in a number of processes including goal-directed cognition, conscious awareness, autonomic regulation, interoception, and somatosensation. While some of these processes are well known in the clinical presentation of migraine (i.e., autonomic and somatosensory alterations), other more complex behaviors in migraine, such as conscious awareness and error detection, are less well described. Since the insula processes and relays afferent inputs from brain areas involved in these functions to areas involved in higher cortical function such as frontal, temporal, and parietal regions, it may be implicated as a brain region that translates the signals of altered internal milieu in migraine, along with other chronic pain conditions, through the insula into complex behaviors. Here we review how the insula function and structure is altered in migraine. As a brain region of a number of brain functions, it may serve as a model to study new potential clinical perspectives for migraine treatment.

A human brain network derived from coma-causing brainstem lesions

OBJECTIVE

To characterize a brainstem location specific to coma-causing lesions, and its functional connectivity network.

METHODS

We compared 12 coma-causing brainstem lesions to 24 control brainstem lesions using voxel-based lesion-symptom mapping in a case-control design to identify a site significantly associated with coma. We next used resting-state functional connectivity from a healthy cohort to identify a network of regions functionally connected to this brainstem site. We further investigated the cortical regions of this network by comparing their spatial topography to that of known networks and by evaluating their functional connectivity in patients with disorders of consciousness.

RESULTS

A small region in the rostral dorsolateral pontine tegmentum was significantly associated with coma-causing lesions. In healthy adults, this brainstem site was functionally connected to the ventral anterior insula (AI) and pregenual anterior cingulate cortex (pACC). These cortical areas aligned poorly with previously defined resting-state networks, better matching the distribution of von Economo neurons. Finally, connectivity between the AI and pACC was disrupted in patients with disorders of consciousness, and to a greater degree than other brain networks.

CONCLUSIONS

Injury to a small region in the pontine tegmentum is significantly associated with coma. This brainstem site is functionally connected to 2 cortical regions, the AI and pACC, which become disconnected in disorders of consciousness. This network of brain regions may have a role in the maintenance of human consciousness.

Distinct Global Brain Dynamics and Spatiotemporal Organization of the Salience Network

One of the most fundamental features of the human brain is its ability to detect and attend to salient goal-relevant events in a flexible manner. The salience network (SN), anchored in the anterior insula and the dorsal anterior cingulate cortex, plays a crucial role in this process through rapid detection of goal-relevant events and facilitation of access to appropriate cognitive resources. Here, we leverage the subsecond resolution of large multisession fMRI datasets from the Human Connectome Project and apply novel graph-theoretical techniques to investigate the dynamic spatiotemporal organization of the SN. We show that the large-scale brain dynamics of the SN are characterized by several distinctive and robust properties. First, the SN demonstrated the highest levels of flexibility in time-varying connectivity with other brain networks, including the frontoparietal network (FPN), the cingulate–opercular network (CON), and the ventral and dorsal attention networks (VAN and DAN). Second, dynamic functional interactions of the SN were among the most spatially varied in the brain. Third, SN nodes maintained a consistently high level of network centrality over time, indicating that this network is a hub for facilitating flexible cross-network interactions. Fourth, time-varying connectivity profiles of the SN were distinct from all other prefrontal control systems. Fifth, temporal flexibility of the SN uniquely predicted individual differences in cognitive flexibility. Importantly, each of these results was also observed in a second retest dataset, demonstrating the robustness of our findings. Our study provides fundamental new insights into the distinct dynamic functional architecture of the SN and demonstrates how this network is uniquely positioned to facilitate interactions with multiple functional systems and thereby support a wide range of cognitive processes in the human brain.

Human cognitive versatility is supported by a distinct, highly flexible, yet stable, dynamic brain organization of the salience network and its interactions with multiple other functional systems.

One of the most distinguishing features of the human brain is its ability to detect and attend to salient events in the environment. The salience network—a core large-scale brain network anchored in the anterior insula and the dorsal anterior cingulate cortex—is thought to play a crucial role in this process. To gain insights into the mechanisms that support this complex set of functions carried out by the salience network, we analyzed state-of-the-art fMRI data collected during multiple sessions with subsecond resolution and mapped dynamic time-varying functional interactions among the key neural components within the salience network and between the salience network and other core brain networks. We show that the large-scale brain dynamics of the salience network is characterized by several distinctive, behaviorally relevant, and robust properties, highlighting its highly flexible yet stable organization. Our findings provide fundamental new insights into the dynamic functional architecture of the salience network and demonstrate how it is uniquely positioned to facilitate interactions with multiple functional systems and thereby support cognitive flexibility.

Efficacy of memantine on neuropsychiatric symptoms associated with the severity of behavioral variant frontotemporal dementia: A six-month, open-label, self-controlled clinical trial

Previous studies have focused on the curative effects of memantine in patients with mild-to-moderate frontotemporal lobar degeneration (FTLD); however, its benefits in patients with moderate-to-severe FTLD have not been investigated. The present study explores the behavioral, cognitive and functional effects of memantine on behavioral variant frontotemporal dementia (bvFTD) in patients with mild and moderate-to-severe stage bvFTD. A total of 42 patients with bvFTD completed a 6-month treatment plan of 20 mg memantine daily in an open-label, self-controlled clinical trial. Patients were divided into two groups according to their Mini-Mental State Examination (MMSE) score: Mild (score, 21-26); and moderate-to-severe (score, 4-20). Primary endpoints included Neuropsychiatric Inventory Questionnaire (NPI-Q) and Clinic Dementia Rating (CDR) scores, and secondary endpoints comprised Neuropsychiatric Inventory Caregiver Distress Scale (NPI-D), MMSE, Montreal Cognitive Assessment (MoCA), Activity of Daily Life (ADL) and Hamilton Depression Rating Scale (HAMD) scores. Memantine treatment had no effect on overall NPI-Q scores, with the exception of the agitation subdomain in all patients with bvFTD. However, patients with moderate-to-severe bvFTD exhibited a better performance than patients with mild bvFTD, demonstrated by improved NPI-Q total scores and subscales of agitation, depression, apathy and disinhibition. In the moderate-to-severe group, CDR and HAMD scores remained stable, but MMSE, MoCA and ADL scores were reduced after 6 months of treatment. Memantine was well-tolerated in patients. In conclusion, patients with moderate-to-severe bvFTD responded significantly better to memantine in comparison to patients with mild bvFTD with regard to their neuropsychiatric scores, while memantine did not present any cognitive or functional benefits in patients with mild bvFTD. A randomized, double-blind, placebo-controlled clinical trial with a larger number of patients is required to verify these promising results for patients with moderate-to-severe bvFTD.

Functional Divergence of the Nuclear Receptor NR2C1 as a Modulator of Pluripotentiality During Hominid Evolution

Genes encoding nuclear receptors (NRs) are attractive as candidates for investigating the evolution of gene regulation because they (1) have a direct effect on gene expression and (2) modulate many cellular processes that underlie development. We employed a three-phase investigation linking NR molecular evolution among primates with direct experimental assessment of NR function. Phase 1 was an analysis of NR domain evolution and the results were used to guide the design of phase 2, a codon-model-based survey for alterations of natural selection within the hominids. By using a series of reliability and robustness analyses we selected a single gene, NR2C1, as the best candidate for experimental assessment. We carried out assays to determine whether changes between the ancestral and extant NR2C1s could have impacted stem cell pluripotency (phase 3). We evaluated human, chimpanzee, and ancestral NR2C1 for transcriptional modulation of Oct4 and Nanog (key regulators of pluripotency and cell lineage commitment), promoter activity for Pepck (a proxy for differentiation in numerous cell types), and average size of embryological stem cell colonies (a proxy for the self-renewal capacity of pluripotent cells). Results supported the signal for alteration of natural selection identified in phase 2. We suggest that adaptive evolution of gene regulation has impacted several aspects of pluripotentiality within primates. Our study illustrates that the combination of targeted evolutionary surveys and experimental analysis is an effective strategy for investigating the evolution of gene regulation with respect to developmental phenotypes.

The Clinical Applicability of Functional Connectivity in Depression: Pathways Toward More Targeted Intervention

Resting-state functional magnetic resonance imaging provides a noninvasive method to rapidly map large-scale brain networks affected in depression and other psychiatric disorders. Dysfunctional connectivity in large-scale brain networks has been consistently implicated in major depressive disorder (MDD). Although advances have been made in identifying neural circuitry implicated in MDD, this information has yet to be translated into improved diagnostic or treatment interventions. In the first section of this review, we discuss dysfunctional connectivity in affective salience, cognitive control, and default mode networks observed in MDD in association with characteristic symptoms of the disorder. In the second section, we address neurostimulation focusing on transcranial magnetic stimulation and evidence that this approach may directly modulate circuit abnormalities. Finally, we discuss possible avenues of future research to develop more precise diagnoses and targeted interventions within the heterogeneous diagnostic category of MDD as well as the methodological limitations to clinical implementation. We conclude by proposing, with cautious optimism, the future incorporation of neuroimaging into clinical practice as a tool to aid in more targeted diagnosis and treatment guided by circuit-level connectivity dysfunction in patients with depression.

Ecstatic Epileptic Seizures: A Glimpse into the Multiple Roles of the Insula

Ecstatic epileptic seizures are a rare but compelling epileptic entity. During the first seconds of these seizures, ecstatic auras provoke feelings of well-being, intense serenity, bliss, and "enhanced self-awareness." They are associated with the impression of time dilation, and can be described as a mystic experience by some patients. The functional neuroanatomy of ecstatic seizures is still debated. During recent years several patients presenting with ecstatic auras have been reported by others and us (in total n = 52); a few of them in the setting of presurgical evaluation including electrical brain stimulation. According to the recently recognized functions of the insula, and the results of nuclear brain imaging and electrical stimulation, the ecstatic symptoms in these patients seem to localize to a functional network centered around the anterior insular cortex, where we thus propose to locate this rare ictal phenomenon. Here we summarize the role of the multiple sensory, autonomic, affective, and cognitive functions of the insular cortex, which are integrated into the creation of self-awareness, and we suggest how this system may become dysfunctional on several levels during ecstatic aura.

Decreased Intra- and Inter-Salience Network Functional Connectivity is Related to Trait Anxiety in Adolescents

Objective: Adolescence is a critical period for the vulnerability of anxiety. Imaging studies focusing on adolescents' susceptibility to anxiety suggest that the different development trajectories between the limbic system and the executive control system may play important roles in this phenomenon. However, few studies have explored the brain basis of this susceptibility from the perspective of functional networks. The salience network (SN) consists of a series of key limbic and prefrontal regions that are engaged in the development of anxiety, such as the amygdala, anterior insula (AI), and dorsal anterior cingulate cortex (dACC). Intra- and inter-network connections in this system play essential roles in bottom-up attention and top-down regulation of anxiety, nevertheless, little is known about whether the SN-centered connections are associated with trait anxiety (i.e., susceptibility to anxiety) in adolescents.

Method: Here, we applied resting-state functional magnetic resonance imaging (fMRI) to explore the relationship between intra- and inter-network functional connectivity (FC) of the SN and trait anxiety in adolescents using the amygdala, AI and dACC as the regions of interest (ROI).

Results: We found that trait anxiety levels were inversely associated with both characteristic AI-dACC FC in the SN and distributed inter-network FC between the SN and multiple functional systems, which included the default mode network and the executive control network.

Conclusions: Our results indicate that weaker intra- and inter-network FC of the SN was linked to higher trait anxiety among adolescents, and it may underlie altered salience processing and cognitive regulation.

Alterations of neocortico-limbic association fibers and correlation with diet in prediabetes diagnosed by impaired fasting glucose

PURPOSE

To assess the existence of alterations in the micro-integrity of the fasciculus in prediabetic subjects. The issue of micro-integrity in white matter tracts has not been adequately addressed in prediabetes.

MATERIALS AND METHODS

Sixty-four prediabetic subjects and 54 controls were enrolled. All participants completed 24-hour diet records and 3-day diet records and received diffusion tensor imaging at 3T. The data for white matter micro-integrity were analyzed and compared between prediabetic subjects and controls with age and gender as covariates. In addition, voxel-wise regression between white matter micro-integrity, diet, and preprandial glucose levels were used to explore the relationship between white matter micro-integrity and diet or serum glucose levels.

RESULTS

We found that prediabetic subjects had significant reductions in the micro-integrity of bilateral anterior thalamic radiation, left inferior longitudinal fasciculus, and left superior longitudinal fasciculus (corrected P < 0.05). In addition, total carbohydrate intake amount and preprandial serum glucose levels were negatively correlated with the micro-integrity in the left inferior longitudinal fasciculus and left anterior thalamic radiation (r: -0.47, corrected P < 0.05).

CONCLUSION

Restrictive alterations in the white matter micro-integrity of the anterior thalamic radiation and inferior and superior longitudinal fasciculi might represent the initial "hot spots" for white matter tract alterations, which might play a role in the development of prediabetes. J. Magn. Reson. Imaging 2016;43:1500-1506.

CHANGES IN REGIONAL BRAIN ACTIVATION RELATED TO DEPRESSIVE STATE: A 2-YEAR LONGITUDINAL FUNCTIONAL MRI STUDY

BACKGROUND

Abnormal brain activations during processing of emotional facial expressions in depressed patients have been demonstrated. We investigated the natural course of brain activation in response to emotional faces in depression, indexed by functional magnetic resonance imaging (fMRI) scans preceding and following change in depressive state. We hypothesized a decrease in activation in the amygdala, anterior cingulate cortex (ACC), and insula with a decrease in depressive pathology.

METHODS

A 2-year longitudinal fMRI study was conducted as part of the Netherlands Study of Depression and Anxiety. We included 32 healthy controls and 49 depressed patients. During the second scan, 27 patients were in remission (remitters), the other 22 were not (nonremitters). All participants viewed faces with emotional expressions during scanning.

RESULTS

Rostral ACC activation during processing of happy faces was predictive of a decrease in depressive state (PFWE = .003). In addition, remitters showed decreased activation of the insula over time (PFWE = .016), specifically during happy faces. Nonremitters displayed increased abnormalities in emotion recognition circuitry during the second scan compared to the first. No effect of selective serotonin reuptake inhibitor use was observed.

CONCLUSIONS

Our results demonstrate that rostral ACC activation may predict changes in depressive state even at 2-year outcome. The association between change in depressed state and change in insula activation provides further evidence for the role of the insula in a network maintaining emotional and motivational states.

Inter-individual variability in metacognitive ability for visuomotor performance and underlying brain structures

Metacognition refers to the ability to discriminate between one's own correct and incorrect decisions. The neurobiological underpinnings of metacognition have mainly been studied in perceptual decision-making. Here we investigated whether differences in brain structure predict individual variability in metacognitive sensitivity for visuomotor performance. Participants had to draw straight trajectories toward visual targets, which could unpredictably deviate around detection threshold, report such deviations when detected, and rate their confidence level for such reports. Structural brain MRI analyses revealed that larger gray-matter volume (GMV) in the left middle occipital gyrus, left medial parietal cortex, and right postcentral gyrus predicted higher deviation detection sensitivity. By contrast, larger GMV in the right prefrontal cortex but also right anterior insula and right fusiform gyrus predicted higher metacognitive sensitivity. These results extend past research by linking metacognitive sensitivity for visuomotor behavior to brain areas involved in action agency (insula), executive control (prefrontal cortex) and vision (fusiform).

Possible functional links among brain- and skull-related genes selected in modern humans

The sequencing of the genomes from extinct hominins has revealed that changes in some brain-related genes have been selected after the split between anatomically-modern humans and Neanderthals/Denisovans. To date, no coherent view of these changes has been provided. Following a line of research we initiated in Boeckx and Benítez-Burraco (2014a), we hypothesize functional links among most of these genes and their products, based on the existing literature for each of the gene discussed. The genes we focus on are found mutated in different cognitive disorders affecting modern populations and their products are involved in skull and brain morphology, and neural connectivity. If our hypothesis turns out to be on the right track, it means that the changes affecting most of these proteins resulted in a more globular brain and ultimately brought about modern cognition, with its characteristic generativity and capacity to form and exploit cross-modular concepts, properties most clearly manifested in language.

Insula-Dorsal Anterior Cingulate Cortex Coupling is Associated with Enhanced Brain Reactivity to Smoking Cues

The insula plays a critical role in maintaining nicotine dependence and reactivity to smoking cues. More broadly, the insula and the dorsal anterior cingulate cortex (dACC) are key nodes of the salience network (SN), which integrates internal and extrapersonal information to guide behavior. Thus, insula-dACC interactions may be integral in processing salient information such as smoking cues that facilitate continued nicotine use. We evaluated functional magnetic resonance imaging (fMRI) data from nicotine-dependent participants during rest, and again when they viewed smoking-related images. Greater insula-dACC coupling at rest was significantly correlated with enhanced smoking cue-reactivity in brain areas associated with attention and motor preparation, including the visual cortex, right ventral lateral prefrontal cortex, and the dorsal striatum. In an independent cohort, we found that insula-dACC connectivity was stable over 1-h delay and was not influenced by changes in subjective craving or expired carbon monoxide, suggesting that connectivity strength between these regions may be a trait associated with heightened cue-reactivity. Finally, we also showed that insula reactivity to smoking cues correlates with a rise in cue-reactivity throughout the entire SN, indicating that the insula's role in smoking cue-reactivity is not functionally independent, and may actually represent the engagement of the entire SN. Collectively, these data provide a more network-level understanding of the insula's role in nicotine dependence and shows a relationship between inherent brain organization and smoking cue-reactivity.

Finding the self by losing the self: Neural correlates of ego-dissolution under psilocybin

Ego-disturbances have been a topic in schizophrenia research since the earliest clinical descriptions of the disorder. Manifesting as a feeling that one's "self," "ego," or "I" is disintegrating or that the border between one's self and the external world is dissolving, "ego-disintegration" or "dissolution" is also an important feature of the psychedelic experience, such as is produced by psilocybin (a compound found in "magic mushrooms"). Fifteen healthy subjects took part in this placebo-controlled study. Twelve-minute functional MRI scans were acquired on two occasions: subjects received an intravenous infusion of saline on one occasion (placebo) and 2 mg psilocybin on the other. Twenty-two visual analogue scale ratings were completed soon after scanning and the first principal component of these, dominated by items referring to "ego-dissolution", was used as a primary measure of interest in subsequent analyses. Employing methods of connectivity analysis and graph theory, an association was found between psilocybin-induced ego-dissolution and decreased functional connectivity between the medial temporal lobe and high-level cortical regions. Ego-dissolution was also associated with a "disintegration" of the salience network and reduced interhemispheric communication. Addressing baseline brain dynamics as a predictor of drug-response, individuals with lower diversity of executive network nodes were more likely to experience ego-dissolution under psilocybin. These results implicate MTL-cortical decoupling, decreased salience network integrity, and reduced inter-hemispheric communication in psilocybin-induced ego disturbance and suggest that the maintenance of "self"or "ego," as a perceptual phenomenon, may rest on the normal functioning of these systems.